Sensing and imaging systems are used by researchers in the academic, pharmaceutical, and biotechnology sectors to characterize biomolecular interactions. These platforms are used in a number of areas, such as antibody characterization, proteomics, vaccines, immunogenicity, and biopharmaceutical development and production. Numerous commercial biosensor instruments exist on the market, such as label-free biosensors and fluorescent microarray scanners. Commercially available label-free biosensor instruments are typically limited by the low throughput of the two-dimensional fluid delivery systems. Currently, some label-free biosensors employ microfluidic systems to deliver the sample to the sensing or imaging surface. The use of 2D flow delivery limits the number of samples that can be delivered simultaneously to the sensor surface. Most commercial label free biosensors employ 1 to 8 channels, each of which can monitor a binding interaction in a one-to-one approach, i.e. one biomolecule in solution (the analyte) being exposed to one biomolecule on the sensor surface (the ligand). This format does allow for a one-to-many approach if biomolecules are run sequentially, but sample consumption and assay time will increase accordingly.
Another common approach used by biosensor platforms is the printing of biomolecules in a microarray format prior to loading into the biosensor or imaging system. Common printing approaches include pin printing, piezo printing, and microfluidic array printing. After printing, the chip is loaded into the biosensor and a 2D flow cell is applied to inject analyte over the microarray of samples, in a one-to-many approach. This enables multiplexing of a single analyte injection against a panel of surface-immobilized ligands, conserving sample and decreasing assay time. However, these instruments are not well suited for assays where the biomolecule cannot be easily tethered to the surface without compromising its binding profile, such as small molecule drug compounds. Further, screening large panels of ligands may require separate printing and loading of sensor chips, which often will require a manual intervention and chip stabilization. Microarray experiments also expose the sensing/imaging surface and biomolecules to air during the printing process. Many of the analytes and targets used in microarray experiments are sensitive and can be damaged by being exposed to air or other buffers that are dissimilar to the fluid environment of biological systems.